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  <script>
    // 根据位置返回字符
    // 1. charAt(index) 根据位置返回字符
    var str = 'Rose is intellectual';
    console.log(str.charAt(8));
    for (var i = 0; i < str.length; i++) {
      console.log(str.charAt(i));
    }

    // 2.  charCodeAt(index)  返回相应索引号的字符ASCII值，目的：判断用户按了哪个键
    console.log(str.charCodeAt(2)); // 115

    // 3.str[index] H5 新增的
    console.log(str[0]);

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